John Maynard Keynes is famous for his private life and associations with Bloomsbury and famous, too, as the economist who campaigned for public works between the wars, and revolutionised economics with his General Theory. A biographer of Keynes has to straddle two very different worlds, and it is one measure of Robert Skidelsky’s achievement that he writes with equal authority of both in this deeply researched and densely textured book. But what marks out his work as truly masterly is his portrayal of the interplay between the private and the public in Keynes, the tensions between the two, and the dynamism released by the growing fusion between the two halves of his nature.

There was a phase of his youth, before the First World War, in which Keynes gave himself over to love, learning and the arts. These early passions were never abandoned, but gradually they were subsumed into the life of an economic statesman. By 1920, the date at which Skidelsky begins the second volume of his Life, Keynes was in a state of transition. His wartime experience as a Treasury official had given him the entrée to Whitehall and the City, and whetted his appetite for power and influence. Though he returned to Cambridge to resume his fellowship at King’s, he was often to be seen, with his bowler-hat and brief-case, hurrying off to London for a board meeting or an appointment with the Chancellor of the Exchequer.

The passionate, and of necessity highly secret, homosexuality of the pre-war days was fading. His last male love was the Cambridge undergraduate Sebastian Sprott, who competed for a time with the rival attractions of the Russian ballerina Lydia Lopokova. But the affair with Sprott appears to have been somewhat tepid. The relationship with Lydia was passionate and any suspicion that his marriage was an arrangement of convenience is swept away by Skidelsky. Though Bloomsbury disapproved of Lydia’s somewhat limited range of conversation and sweetly disordered use of English, she won the love of the frustrated artist in Keynes, and bowled him over with sheer physical affection. ‘I gobble you my dear Maynard,’ she wrote. ‘I retain infinitely your warm wet kisses.’ Nor was Lydia without political judgment. During the General Election of 1931, when MacDonald and Baldwin joined forces in the National Government, she wrote: ‘I have rolled my eyes on the manifestos of Ramsey and Stanley, but they close instantaneously with dreariness.’

Through his marriage to Lydia, Keynes broke with the more neurotic aspects of Bloomsbury. But in another sense his marriage was a testimony to the aesthetic and Bloomsbury side of his nature. So enamoured was Keynes of Lydia that he organised a ballet company, the Camargo, to provide her with a stage; and later, when she turned to acting, the Cambridge Arts Theatre. More generally, however, his love of the arts was one of the mainsprings of his public life. Keynes believed that the liberal arts could not survive in the long run without external protection. They were the spiritual core of the liberal civilisation in which he had been raised. But the secure foundations on which that civilisation had rested up to 1914 had been severely damaged by the Great War. Bolshevism and barbarism were all around and henceforth it would be necessary to preserve by artifice and ingenuity what had previously been taken for granted. Without economic stability no liberal society could exist: but economic stability would have to be organised by economists. This explains Keynes’s great polemic against the Versailles Treaty and its authors: The Economic Consequences of the Peace.